Piezo-electric detonation initiator system



y 23, 5 T. Q. CICCONE ETAL. 3,320,890

PIEZO-ELECTRIC DETONATION INITIATOR SYsTF-M Filed May 6, 1965 INVENTORS- THOMAS C). CICCONE WILLIAM E. PERKINS Ha. w-

United States Patent 3,3205% PIEZO-ELECTRIC DETONATION INITIATOR SYSTEM Thomas Q. Ciccone, Langhorne, Pa, and Wiiiiam E. Perkins, Runnemede, Nl, assignors to the United States of America as represented by the Secretary of the Army Filed May 6, 1965, Ser. No. 453,845 Claims. (Cl. 102-702) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to us of any royalty thereon.

The present invention relates to detonation initiator or firing systems and apparatus for propellant and/or explosive charges and devices.

It is a primary object of this invention to provide an improved detonation initiator or firing system of the type referred to which is adapted for use with electrical control means in a unitary apparatus, while being free of complexities and reliable and safe in operation.

It is also an object of this invention to provide an improved detonation or firing system in unitary form wherein the advantages of electrical firing and conventional fuse line control are combined for reliable and safe operation.

It is also a further and important object of this invention to provide a compact unitary detonation initiator or firing device or cartridge of the piezo-electric type which embodies said improved system and is adapted to be actuated in connection with conventional fuse lines while being reliable and safe in operation and handling In airplanes, missiles and space vehicles generally, as well as ground operations involving the firing of charges of various types, numerous propellant and explosive devices and charges are employed. For each device there is the immediate requirement that it is to be reliable in operation, safe in handling and comparatively easy to actuate in a firing system. It is also desirable, generally, that the device be compact, lightweight and free of complexities.

For many cartridges, including those currently in use, an electrical firing control system has been considered undesirable. This is for the reason that, among other things, long wires or leads for remote control may act as antennae elements to pick up radio-frequency signals and occasionally fire the connected electrical detonation devices prematurely and possibly dangerously. For this reason, alternative systems have been and are being sought with the possibility that they may be safer in operation and yet have a degree of firing reliability required.

One of the systems considered involves the use of a type of detonating device known as a Mild Detonating Fuse. With this system, however, it is difficult to transfer the energy of the fuse and/or its booster detonating waves to a closed cartridge and continue the chain reaction to completion. Two different improvements have been suggested for this system and comprise first, using the output energy of the fuse/booster to actuate a percussion firing mechanism, and secondly, using the output of the fuse/booster to initiate a shock-sensitive composition through a cartridge barrier. In both of these alternatives a considerable amount of development is necessary to obtain what might be called acceptable performance. In the first case, the booster would have to be modified to propel a firing pin, and in the second suggestion, a shock-sensitive composition would have to be developed.

Accordingly, a third possibility for effective and safe operation of a system of this type may be provided in 3,32%,890 Patented May 23, 1967 accordance with the invention through the use of the initiator means in accordance therewith.

Fuse lines of any desired length may be used and actuated or detonated at the far end to fire progressively along the line to a booster or explosive cartridge which generates a shock wave. This acts upon a wave spring to force movable piston means against a piezo-electric voltage generator element to produce a high voltage charge as stored energy. This piezoelectric energy is discharged through and fires an electrical primer associated therewith, and this initiates the charge of whatever typ r The piezo-electric generator unit is adapted for receiving and being actuated by a pair of regular progressive combustion type fuse lines for safety against electrical signal pickup, and is compact and simplified in construction as well as being lightweight and safe to handle in storage and in assembly.

The invention will further be understood from the following description when considered with reference to the accompanying drawing, and its scope is pointed out in the appended claims.

In the drawing, the single figure is a cross-sectional view of a cylindrical piezo-electric cartridge in accordance with the invention and a firing control system and charge element connnected therewith for complete operation and illustration of its use.

Referring to the drawing, a piezo-electric cartridge 5 comprises a cylindrical outer hollow casing or body 6 having an enlarged hexagonal or like configuration as indicated at 7 for holding it with a wrench or other like device. This is provided substantially midway between the ends of the said casing or body, which is threaded at one end to receive a flanged retainer or cover 9 adapted to be threaded thereon, as indicated, and lock in place one or more mild detonating fuse boosters or other suitable explosive cartridges of which two ar shown at 10 and 11. These provide detonating terminations for a similar number of fuse lines 13 and 14, of conventional or of the mild detonating fuse type, having the usual ignitable powder cores or the like for progressive ignition and timing by the flow of the ignition along the length thereof from a remote control station or firing control means indicated at 12. The latter may be of any desired construction for selecting and firing either or both of the fuse lines either manually or by timing as is known.

In the present example, it is adapted for ground use and control for firing a charge 15 in an explosive device 16 as indicated. Safety selection means as indicated at 17 may be set to the firing position as indicated and fired either individually or simultaneously by actuation of a firing button or other similar device as indicated at 18. In an airplane, a missile or other space vehicle, for example, the initiation of the fuse line selected may be entirely by remote control from ground or by other means, as is known in such vehicles. Since the firing control is not part of the invention, further description is believed to be unnecessary. In operation, either fuse line is selected for initiating the firing at a remote end thereof which may be at some distance and the progressive burning of the fuse line finally fires the booster or cartridge as at 10 or 11 within the device.

The booster cartridges 10 and 11 and like firing elements for terminating the fuse lines are locked in place by the retainer 9 as it is tightened on the end of the casing 6 and bears against a perforated plate 20 which in turn engages and locks with a flange 21 or the like on each cartridge. The cartridges are held in place within the confines of the casing by suitable spacer elements 23 on each side and a center spacer element 24 as indicated. This arrangement facilitates assembly and materially aids in holding the booster cartridges securely within the body of the casing 6.

The inner ends of the cartridges and 11 bear against a disc spring 25 through which they apply pressure to a movable piston element 27, and cause it to bear firmly against a piezo-electric element 28 for which it also provides one grounded electrode. The piston element 27 is circular and relatively short and disc-like. It smoothly fits the bore of the casing 6 and moves readily in response to pressure from the wave spring 25.

The piezo-electric crystal element 28 is a flat disc, as indicated, and is provided with an insulated second electrode on the opposite side thereof as indicated at 30. This and its connected spring terminal elements 31 is insulated from the casing by a series of ring and disc insulating elements as indicated at 29 and 30 respectively.

The spring contact 31 engages an electric detonation initiator element 34, such as a primer, which is mounted in and insulated from a detonation cartridge 35 having a detonating charge 36 adjacent to an end opening 33 in the casing through which the charge is fired.

In the present example the detonating charge is arranged to ignite a powder or other explosive charge in the device 16 which is screw threaded thereon and locked in place as indicated.

The piston element 27 and the piezoelectric element 28 with its connnected electrodal and primer firing and cartridge elements are all located in coaxial alignment along the axis of the casing as indicated.

When either of the fuse lines, which may be of the MDF type, are ignited to actuate or fire either of the booster cartridges 19 or 11, a shock wave is generated thereby and acts upon the wave spring 25 to force the piston element 27 against the piezoelectric element 28. The pressure acting on this element produces a highvoltage charge. This charge is conducted through the contact 31 and delivered to the electric detonation initiator 34, which is a voltage-sensitive device to fire it. The electric initiator in turn ignites the cartridge 35 to fire the detonating or propellant charge 36 therein and complete the functioning of the device 16 by delivery of the burning charge or firing output therefrom through the open end 37 of the casing 6.

This simplified cartridge is easy to operate and to manufacture and is readily assembled as is indicated. It is reliable and safe in operation since it provides a barrier between the charge to be detonated and the fuse lines. It cannot be fired until it receives the electrical charge from the piezoelectric element and this in turn is dependent upon the firing by the booster cartridges. These are fired by the said fuse lines which are insensitive to radio-frequency signals and therefore not subject to accidental firing as in the case of long electrical lines as herein before referred to. This device thus meets a basic requirement that it be reliable in operation, safe in handling, and comparatively easy to actuate. It is compact, light in weight, and free of complexities, all as desired.

We claim:

1. A unitary initiator apparatu for propellant and explosive charges and comprising in combination,

a tubular casing,

a movable piston element mounted coaxially in said casing,

a piezo-electric element engaged by said piston for applying pressure thereto in response to piston movement to generate an output voltage,

means for applying operative firing pressure to said piston element comprising a first and a second detonation initiator cartridge each providing termination means for an ignitable fuse line,

a disc spring interposed between said cartridges and the piston element and engaging said element for distributing the firing pressure thereover,

means in said casing holding said cartridges in contact with said disc spring,

an insulated output electrode for said p-iezo-electric element,

an electric detonation initiator element connected with said electrode to receive a firing voltage therefrom,

a detonator cartridge having a detonating charge p0sitioned for ignition or firing by said initiator element, and

means for applying the firing output from the detonator cartridge to an explosive charge to be fired.

2. A unitary piezo-electric detonator apparatus for controlled firing of explosive charges and the like comprising in combination,

an elongated hollow casing,

a movable piston element mounted therein,

detonating means for driving said piston element in an axial direction comprising a pair of booster cartridges adapted for fuse-line ignition and a disc spring element between said cartridges and one end of said piston element to provide pressure distribution from said cartridges to said piston element upon detonation,

a piezo-electric disc, one face engaging the opposite end of said piston element for which it provides an electrode element and a second electrode element on the opposite face thereof and insulated from the casing,

an insulated electric detonation initiator element flexible connected with said second electrode element for receiving a high-voltage firing charge therefrom in response to detonation pressure on said disc, and

a detonator cartridge mounted in alignment with said initiator element for receiving a firing charge therefrom in response to ignition of either booster cartridge in operation.

3. A unitary detonation initiator system for propellant and explosive charges comprising,

a pair of progressive-firing fuse lines terminating each in a detonation booster cartridge,

a piezo-electric cartridge having an elongated tubular casing providing receiving and clamping means for said cartridges at one end and a firing output opening at the opposite end,

a disc-like piston element mounted for movement in said casing in an axial direction in response to axial thrust from either of said cartridges on firing,

a thrust-distributing disc-spring element interposed and providing a thrust-transmitting connection between said piston element and said booster cartridges,

a piezo-electric voltage-generator disc having one face in contact with said piston element to provide grounded electrodal means therefor and to receive relatively high compression and voltage-generating thrust therefrom in response to said piston movement,

means providing a second and insulated electrodal contact with said piezo-electric disc on the opposite face thereof, an insulated electric-detonation initiator element resiliently connected with said second electrodal contact means to receive a firing voltage therefrom, and

a detonating cartridge having a propellant charge aligned with said initiator element for ignition there by and with said output opening to deliver an output firing charge therethrough.

4. A unitary detonator initiator system as defined in claim 3, wherein said fuse lines are provided with selective firing-control means for actuating said lines at the remote ends, and wherein the receiving and clamping means for the detonation booster cartridges includes a threaded screw-on type of flanged cover attached to the casing end and adapted with the casing for holding and References Cited by the Examiner turning with a wrench or the like. UNITED STATES PATENTS 5. A unitary detonat or system as defined in claim 3,

wherein the casing is fitted for attachment at said opgerrara 85 osi'te end to an explosive device holding a working 5 w 1 P 2,972,306 2/1961 Kabik et a1. 102-70.2

charge to be fired, and wherein the output opening in said end is aligned with the explosive device to directly B AM N A. BORCHELT, Primary Examiner. fire Said charge. W. C. ROCH, Assistant Examiner. 

2. A UNITARY PIEZO-ELECTRIC DETONATOR APPARATUS FOR CONTROLLED FIRING OF EXPLOSIVE CHARGES AND THE LIKE COMPRISING IN COMBINATION, AN ELONGATED HOLLOW CASING, A MOVABLE PISTON ELEMENT MOUNTED THEREIN, DETONATING MEANS FOR DRIVING SAID PISTON ELEMENT IN AN AXIAL DIRECTION COMPRISING A PAIR OF BOOSTER CARTRIDGES ADAPTED FOR FUSE-LINE IGNITION AND A DISC SPRING ELEMENT BETWEEN SAID CARTRIDGES AND ONE END OF SAID PISTON ELEMENT TO PROVIDE PRESSURE DISTRIBUTION FROM SAID CARTRIDGES TO SAID PISTON ELEMENT UPON DETONATION, 